Automatic safety-stop for elevators.



N, am W m. l M H JD w 6 w my 7 i v 2:5 m i .u V i, m I g d M ii C a5 u W i 1 a; 8 7 m I q JO 8 m AUTOMATIC SAFETY STOP FOR ELEVATORS.

No Model) UNITED STATES PATENT OFFICE.

JAMES H. JOHNSON, OF NEWARK, NEW JERSEY, ASSIGNOR OF ONE-HALF TO WILLIAM R. WEEKS, OF SAME PLACE.

AUTOMATIC SAFETY-STOP FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 632,415, dated September 5, 1899.

Application filed April 27, 1899. Serial No. 714,669. [No model.)

To all whont it may concern:

Be it known that 1, JAMES H. JOHNSON, a citizen of the United States, residing at Newark, county of Essex, State of New Jersey,

have invented certain new and useful Improvements in Automatic Safety-Stops for Elevators, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

IO The object of the present invention is to furnish auxiliary appliances for use in connection with electric elevators to wholly out off the electric current from the motor and to apply a brake to the armature-shaft in case the hand operating devices become deranged so that the car travels beyond its normal movement. Such auxiliary appliances are arranged to operate automatically as the car approaches the opposite limits of its movement, and especially the upper limit, Where an excessive movement of the car is liable to produce the breakage of the hoist-rope and thus cause the fall of the car.

.Electric elevators are always provided with switching devices for normally operating the electric motor and sometimes with a brake for checking the movement of the armature shaft; but whatever appliances are provided for normally operating the car my invention furnishes an auxiliary cut-out switch and a direct connection from the lever of such switch to the brake-lever, so that in emergencies the current may be cut off from the motor and the brake may be set in operation. To avoid the possibility of derangement, the switchlever and the brake-lever are connected directly by what I term an emergency-cord, and a shifter-rod is connected with such emergency-cord and provided with a block which is pressed by a dog upon the car when it goes beyond its normal limit, so as to move the switch-lever and brake-lever and thus secure the immediate stoppage of the car. The guide-posts for the car, which extend from the top to the bottom of the hoistway, furnish a convenient support for shifter-rods at the top and bottom and close to the side of the car, where a block upon' the rod may be readily engaged by a dog uponthe car. The

shifter-rod may also be arranged in line with the top or bottom of the car, so as to be pressed by the same when it moves beyond its normal travel. In either case the block upon the shifter-rod must be moved out of the path of the dog to permit the rod to be restored to its normal position before the cutout switch can be closed and the brake-lever be released to permit the car to be started.

' My improvements will be understood by reference to the annexed drawings,in which Figure 1 is a diagrammatic representation of a hoistway-car and the required attachments with shifter-rods fixed upon the guidepost near its top and bottom. Fig. 2 is a similar view of the top of the hoistway with the shifter-rod fixed movably above the topv of the car.

The several floors of the building are designated a, the guide-posts b, the car 0, and the hoisting-rope d. The drum upon which such rope is wound is designated 6, the electric motor f, and the armature-shaft g. A brake-wheel his shown upon the armatureshaft, with brake-shoes i, actuated by a lever An auxiliary cut-out switch It is inserted in the motor-circuit and provided with switchlever Z, and a cord m is extended from such switch-lever over a pulley n to the brakelever h. The pull-rope Lb is shown extended through the car and would in practice be connected with the ordinary means for reversing the rotation of the rope-drum e and is provided with the usual balls 11 n at its upper and lower ends to receive the safety-stops near the limit of the cars movement.

The ordinary means for reversing or stopping the motor and which are actuated by the pull-rope u are not shown herein, as they form no part of the presentinvention and may be constructed in any ordinary or suitable 9o manner.

The shifter-rods o and o are fitted movably in bearings 19 upon the guide-posts 1), near its upper and lower ends, respectively, and are separately connected with the cord in by cords q q,.extended over pulleys r 7". Dogs 3 ,9 are fixed upon the car at its top and bot-. tomand corresponding blocks it fixed upon the shifter-rodeo 0 and projected in the path of the dogs. Each of the blocks is so adjusted zoo upon the shifter-rod that if the car exceeds its normal limit of travel the dog engages the corresponding block and shifts the rod 0 or 0, so as to pull the attached rope.

In Fig. l the car 0 is shown a little above its normal limit of travel, and the brake-shoes are shown pressed upon the brake-wheel h and the auxiliary switch opened by the shifting of the lever Z, such actuation of the brake and switch being efiected by the operation of the dog 5 upon the shifter-rod 0. Such movements operate to cut off the'current from the motor and to apply the brake, so as to promptly stop the elevation of the car. To close the switch 70, the block 25 would have to be loosened upon the rod 0, so that the rope m might be slackened and the switch-lever and brake-lever restored to their initial position. The car being then sufficiently lowered the block t can be reset, so as to operate again in a similar emergency. The operation of the shifter-rod 0 at the bottom of the hoistway is precisely similar, as its downward movement produces the same tension upon the cord m as the upper movement of the rod 0.

As my appliances are only brought into use when the other safety-stops fail to operate, I term the cord m an emergency-cord, and such term embraces the connection between the brake-lever J and the switch-lever Z, so that the movement of one by the Sifter-rod necessarily produces a movement of the other.

As my appliances operate only when the car is carried beyond its normal travel, certain of the parts, as the blocks i, may require to be moved or loosened for readjusting the apparatus to a normal condition. The blocks tare shown provided each with a set-screw to loosen it upon the rod 0, if desired; but it is obvious that means may be provided for rotating the rod 0 to turn the block out of the path of the dog, and thus permit the shifting of the rod to close the switch. The car being then returned to its normal position (level with the floor a or a the rod may be turned back again and operated as before. The set screwsuffices to loosen or turn the block upon the rod with the construction shown in Fig. 2; but other means may be employed, and I have therefore shown an alternative construction in Fig. 2, where a portion of the shifterrod is held movably above the top of the car and formed with a jointed block upon its forward end to be actuated normally by a dog projected upwardly from the car. The portion of the shifter-rod held above the car is connected by a cord (extended over suitable pulleys) with the rod 0, and thus operates the switch-lever and brake-lever, as before described.

In Fig. 2 a pulley 1 is shown mounted upon the end of a slide 2, arranged in a vertical guide 3 above the car in line with a dog 4, fixed on the top of the car adjacent to the hoisting-rope (I. With the dog thus situated the thrust or strain upon the car is more central than where the dog projects at one side of the same. The pulley 1 is fitted to the bight of a rope 5, which is carried over pulleys 6 and 7 to bring it in line with the shifterrod 0 and to pull such rod upwardly when the car passes beyondits normal limit. The slide serves as the actuating portion of the shifterrod, and its lower end is hinged to form a removable block, which may be bent out of line with the dog 4, as indicated by dotted lines 2, to permit the readjustment of the rod 0 for closing the switch to restore the car to its normal position, and broad bearing-faces are formed upon the dog and the lower end of the slide to hold the parts securely in position and prevent the accidental bending of the hinge when the dog presses the slide npwardly.

My appliances are adapted for application to any existing electric elevator in addition to those already provided to furnish an auxiliary safety device, so that if all other means fail the motor may be positively stopped.

The rope 72 (shown in Fig. 1) may be connected with a brake-lever hby a spiral spring, as is common, to prevent the rope being overstrained when the car moves after the brake is first pressed upon the brake-wheel. Such construction is not illustrated, as it is already well known and operates to maintain an elastic pressure upon the brake until. the car comes to rest.

The shifter-rod 0 is shown extended downward along the guide-post b as nearly as possible to the switch-shifter rope m, thus avoiding as much as possible the slack which occurs in long rope connections and the variations produced by the expansion and contraction of ropes. The shifter-rod 0 is extended upward in a similar manner as far as possible, but is of much less length than the rod 0, as it lies much nearer to the hoisting machinery; but such features of the construction may be altered to suit the existing conditions.

Having thus set forth the nature of the invention, what is claimed herein is- 1. In an elevator, the combination, with the hoistway and the car movable therein, and an electric motor, drum and rope for hoisting the car, with appliances for normally controlling the motor, of an auxiliary switch with lever for cutting off the current from the motor, a brake-wheel and brake-lever for checking the rotations of the motor, an emergencycord directly connecting the switch-lever and brake-lever, a shifter-rod connected by a rope to such emergency-cord, a dog upon the car and a block upon the shifter-rod arranged in the path of such dog to be moved when the car passes beyond its normal travel, substantially as herein set forth.

2. In an elevator, the combination, with the hoistway and the car movable therein, and an electric motor, drum and rope for hoisting the car, with appliances for normally controlling the motor, of an auxiliary switch with lever for cutting off the current from the motor, a brake-wheel and brake-lever for checking the rotations of the motor, an emergencycord directly connecting the switch-lever and brake-lever, a shifter-rod connected bya rope to such emergency-cord, a dog upon the car for moving the rod at the extreme limit of the cars travel, and a block held upon such rod normallyin the path of the rod, and adapted for turning out of line with the dog, to restore the rod to its normal position When displaced by the dog, substantially as herein set forth.

3. In an elevator, the combination, with the hoistway and the car movable therein, and an electric motor, drum and rope for hoisting the car, with appliances for normally controlling the motor, of an auxiliary switch with lever for cutting off the current from the motor, a brake-Wheel and brake-lever for checking the rotations of the motor, an emergencycorddirectly connecting the switch-lever and brakedever, two shifter-rods supported movably near the opposite limits of the cars movement, and independently connected to the emergency-cord, and means upon the car for moving one of such shifter-rods near each limit of the cars travel, substantially as herein set forth.

In testimony whereof I have hereunto set my hand in the presence of two subscribing Witnesses.

JAMES H. JOHNSON. Witnesses:

L. LEE, THOMAS S. CRANE. 

